SU1286399A2 - Grinding head - Google Patents

Abstract

The invention relates to a machine tool industry, mainly to intra-grinding heads, and allows improving the accuracy of machining parts by reducing the magnitude of the elastic deformations of the spindle under the action of cutting forces. Plates 5 and 6 with equally bent ends rigidly connected to bushings 7 and 8, brought into contact with each other on the straight section by their convex side, perform the function of a rigid limiter of the radial displacements of the spindle 2 with the grinding wheel. The preliminary elastic tension of the plates 5 and 6 in the radial direction and their stress state in the supports 3 eliminates the possibility of a gap in the middle part between the plates and compensates for the reduction of their length at the time of the torsion axis vibration of the spindle 2. 4 Il. a (L

Description

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The invention relates to a machine tool, mainly to intra-grinding heads.

The purpose of the invention is to improve the accuracy of the workpiece by increasing the radial stiffness of the elastic spindle supports.

Figure 1 shows a grinding head, a slit; figure 2 - section aa in figure 1; on fig.Z - section BB in figure 1; figure 4 is an elastic element of the support; on fig.Z - characteristics of the stiffness coefficients of elastic elements.

The grinding head consists of a housing 1 and a spindle 2 mounted on elastic supports 3 in bearings

4 remarks Each of the supports 3 is made in the form of an impeller with plate-shaped lobes 5 and 6, which are connected to the inner and outer sleeves 7 and 8 of support 3. The plates 5 and 6 are bent equally along the radius R, contain a straight line in the middle and are facing to each other convex sides. In addition, the plates

5 and 6 are mirrored one relative to the other with the contact in the middle part on the straight-line portion. The ends of the plates bent along the radius R are connected to the bushings 7 and 8 in a stressed state with a radial force

eat, exceeding cutting power. Equally bent along the radius R, the plates 3 and 6, brought into contact with each other, provide a high radial rigidity of the supports 3, coaxially distributed. the position of the sleeves 7 and 8, the uniform distribution of forces on the support 3 and the high accuracy of the supports. Support 3 with plates 3 and 6, located with a gap between their middle part, has a small radial rigidity. Cylindrical

At the moment of contact of the grinding wheel with the part in the transition process in connection with a lower stiffness of the spindle supports 3 in the axial direction and elastic coordinate connection on the shape of the elastic plates, they simplify their production and allow you to get support for 45 spindle movements in the circumferential and Axes 3 of the same shape and with the same direction, grinding wheel with rigidity characteristics.

moves in axial, circumferential directions.

so in

Plates 3 and 6 (Fig. 4) are of a shchyndric form with a radius R of 12 mm and have a distance f between. ends of 12 mm and a cross section of 8 0.3 mm. The convex side of the plate is brought into contact with each other on

moves in axial, circumferential directions.

50

Moving a circle in the axial direction increases the speed of axial transmission and the pressure between the wheel and the part, and consequently, the force of friction and repair. Opposition forces

straight line length of 3 mm for grinding by moving the spindle

the expense of compression between the sleeves 7 in the presence of an elastic coordinate st the radial direction of the ends of the plates

3 and 6. Connected with sleeves 7 and 8 and I

The vibrations of the spindle introduced into contact with the plasnness cause the damping of the vibration during the transition process.

Tines 5 and 6, rotated at the same angle 60 in the plane of rotation of the spindle about its axis, are possessed by-. are a non-linearly increasing characteristic of the stiffness coefficient in the radial direction, which exceeds the stiffness coefficient of the plates in the direction of the spindle axis by 20-25 times (lines 1 and 2 in FIG. 3). The planes of rectilinear and radially curved sections of all plates 3 and 6 are rotated at the same angle in the plane of rotation of the spindle about its axis. The dimensions of plates 3 and 6 (thickness, width, length, and also the angle of rotation) are chosen from the condition that the stiffness of the plates brought into contact with each other in the circumferential and axial directions is less than ten times their radial rigidity, and also less than several times, for example up to three times, the bending stiffness of the spindle. Grinding spindle 2 with a circle mounted on elastic supports 3 has the lowest natural frequency in the circumferential and axial directions. In this case, the contact plane of the rectilinear sections of the plates 3 and 6 is rotated into

the plane of rotation of the spindle at the same angle in the range 43 73 relative to the axis of the spindle. Due to this, the stiffness of the plates 3 and .6 and the elastic supports 3 are lower in the axial direction and the elastic coordinate of the torsional-axial oscillations of the circle with the spindle is ensured during the grinding process.

The grinding head works as follows.

At the moment of contact of the grinding wheel with the part in the transition process in connection with a lower stiffness of the spindle supports 3 in the axial direction and elastic coordinate link in the spindle movements in the circumferential and axial directions, the grinding wheel

spindle movements in the circumferential direction, grinding

moves in axial, circumferential directions.

So

Spindle oscillations are caused by vibration damping during the transition process.

As the cutting force increases, the radial load on the plates 5 and 6 in the supports 3 increases and the length of the contact area between the convex sides of the plates increases. In this case, the rigidity of the plates 5 and 6 and the radial rigidity of the supports 3 as a whole increase several times and the possibility of further radial deformation of the plates is practically excluded. The latter perform the function of a hard limiter of the radial displacements of the spindle 2 with the grinding wheel. The preliminary elastic tension of the plates 5 and 6 in the radial direction and their prestressed state in the supports 3 exclude the possibility of a gap in the middle part between the plates and compensate for the change in their length at the time of the axial-rotational vibrations of the spindle 2, which ensures reliable operation of supports 3 in case of accidental overloads. The high rigidity of the elastic supports 3 in the radial direction reduces the magnitude of the elastic deformations of the spindle under the action of the cutting force and ensures high precision of the workpiece.

Claims (1)

Invention Formula Grinding head auth.St. No. 975363, characterized in that, in order to increase the processing accuracy, the leaf-like petals are made in the form of two elements of a cylindrical shell that are prestressed in the radial direction and have convex sides facing each other and are mirrored one with the other with the possibility of contact in the middle part. A-fl, FIG 2 FB (g.Z. Figm R, KGS um